U.S. patent number 3,644,927 [Application Number 04/828,124] was granted by the patent office on 1972-02-22 for event monitor system.
This patent grant is currently assigned to Gulton Industries. Invention is credited to James Green.
United States Patent |
3,644,927 |
Green |
February 22, 1972 |
EVENT MONITOR SYSTEM
Abstract
An event monitoring system for displaying information of the
condition of a plurality of condition responsive means which may be
electronic switches or relay contacts which have circuit opening
and circuit closing conditions indicating two possible conditions
(i.e., normal and abnormal) of the condition or variable being
monitored. The event monitoring system includes saturable core
devices having respective separate saturable cores most desirably
each carrying a biasing winding and a scanning winding, the biasing
windings being connected in series and the scanning windings being
connected in series. The biasing windings have different numbers of
turns with respect to one another so a predetermined magnitude of
biasing current passing through the series connected biasing
windings will saturate the cores to provide progressively
increasing degrees of saturation in the cores. The series connected
scanning windings have the same or similar numbers of winding turns
as each other scanning winding and a scanning current of
progressively increasing value is delivered to the scanning
windings to develop an oppositely directed progressively increasing
electromagnetic field sequentially to unsaturate the cores at
predetermined current values to cause sequential electrical output
signals to be generated thereby. Associated condition responsive
means are connected to each saturable core device, such as across
each scanning windings, and the condition responsive means is a
normally open switch so closure of the switch will prevent the
unsaturation of the core by the scanning current. The absence of an
electrical output signal at the current value assigned to the core
device involved indicates that the variable involved is normal or
abnormal whichever the case may be.
Inventors: |
Green; James (Los Angeles,
CA) |
Assignee: |
Gulton Industries (Metuchen,
NJ)
|
Family
ID: |
25250977 |
Appl.
No.: |
04/828,124 |
Filed: |
May 27, 1969 |
Current U.S.
Class: |
340/518; 307/413;
365/132; 340/537 |
Current CPC
Class: |
G08B
26/005 (20130101) |
Current International
Class: |
G08B
26/00 (20060101); G08b 026/00 (); G08b
023/00 () |
Field of
Search: |
;340/413,412,181,213Q,213,213.1,168S,174WB |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Habecker; Thomas B.
Claims
I claim:
1. An event monitor system for detecting the presence of an
abnormal state of any one of a number of conditions being
monitored, said system comprising: a first plurality of saturable
core devices each having a winding wound about a separate saturable
magnetic core, said windings being connected in series; means for
initially saturating said cores in a given direction; means for
sequentially driving each magnetic core from a state of saturation
in said given direction to an unsaturated state, the driving of
each magnetic core from saturation in said given direction to an
unsaturated state occurring before the next core is driven from its
initially saturated state to provide a detectable substantial
change in an electrical output in the said winding thereof as the
core thereof is separately driven from its state of saturation;
condition responsive means respectively associated with each of
said plurality of saturable core devices, each of said condition
responsive means being respectively in normal and abnormal
conditions when the condition being monitored is respectively in
normal and abnormal states and in one condition thereof inhibiting
the detectable substantial change in the electrical output of the
associated saturable core device so said electrical output in said
winding thereof is absent at the instant of time when the core
would otherwise be driven from its saturated state; and time and
electrical input responsive means coupled to said windings and
responsive to the presence or absence of an electrical output in
said group of windings at a given time for identifying the
associated saturable core device associated with a condition
responsive means in an abnormal condition.
2. An event monitor system for detecting the state of a number of
conditions being monitored, said system comprising: a first
plurality of saturable core devices each having a winding wound
about a separate saturable magnetic core, said windings being
connected in series; means for initially saturating said respective
cores in a given direction in progressively increasing
predetermined degrees; scanning current means connected to said
series connected winding for generating a progressively increasing
current for sequentially driving each core from a saturated
condition in said given direction to an unsaturated state, the
driving of each magnetic core from saturation in said given
direction to an unsaturated state occuring before the next core is
driven from its initially saturated state to provide a detectable
substantial change in an electrical output in the winding thereof;
condition responsive means respectively associated with each of
said plurality of saturable core devices, each of said condition
responsive means being respectively in normal and abnormal
conditions when the condition being monitored is respectively in
normal and abnormal states and in one condition thereof inhibiting
the detectable substantial change in the electrical output of the
associated saturable core device so said electrical output in said
winding thereof is absent at the instant of time when the core
would otherwise be driven from its saturated state; and time and
electrical output responsive means coupled with said windings and
responsive to the presence or absence of an electrical output in
said group of windings at a given time for identifying the
saturable core device associated with a condition responsive means
in an abnormal condition.
3. An event monitor system according to claim 2 wherein each of
said cores of said saturable core devices are substantially
identical and having windings of progressively increasing numbers
of turns to develop saturating magnetic fields within their
respective cores of correspondingly progressively increasing
magnitude and said scanning current means providing a progressively
increasing current through said windings.
4. An event monitor system according to claim 3 wherein said means
for sequentially driving each magnetic core from a saturation in
said given direction will drive said magnetic core through an
unsaturated state to the opposite state of saturation, the
switchover of each core to the opposite state of saturation
occurring before the next core is driven from its initially
saturated state.
5. An event monitor system according to claim 4 wherein each of
said cores has a rectangular hysteresis characteristic so each core
is driven between opposite states of saturation with a small change
in ampere-turns.
6. An event monitor system according to claim 2 wherein said
condition responsive means is a switch connected across a winding
of each magnetic core device to render the core unresponsive to
said scanning current when the switch is in its closed
condition.
7. An event monitor system according to claim 2 wherein said
windings of said first plurality of saturable core devices are
divided into two groups, one group of windings being wound in one
direction and the other group of windings being wound in the
opposite direction, the said time and amplitude dependent scanning
current developed by said scanning current means is a series of
alternately oppositely directed current signals; one current signal
increasing over a predetermined time interval starting at zero and
increasing to a maximum of one polarity, and the other oppositely
directed current signal increasing over a subsequent predetermined
time interval starting at zero and increasing to a maximum of the
opposite polarity, said one current signal sequentially driving
each core of said one group of windings from a saturated condition
in said given direction through an unsaturated state to the
opposite state of saturation to produce a detectable substantial
change in said electrical output while not effecting a change in
said other group of windings, and said other current signal
sequentially driving each core of said other group of windings from
a saturated condition in said given direction through an
unsaturated state to the opposite state of saturation to produce a
detectable substantial change in said electrical output while not
effecting a change in said one group of windings.
8. An event monitor system according to claim 2 wherein said time
and amplitude dependent scanning current developed by said scanning
current means is a linearly increasing current over a predetermined
time interval which periodically repeats starting from zero and
linearly increasing to a maximum value.
9. An event monitor system according to claim 2 wherein the
detectable substantial change in the electrical output in each of
said windings is produced by a change of state of saturation of the
associated saturable core device.
10. An event monitor system for detecting the state of a number of
conditions being monitored, said system comprising: a first
plurality of saturable core devices each having first and second
windings associated with a separate saturable magnetic core, said
first windings being connected in series with each other to form a
group of biasing windings which, when a given saturating biasing
current flows therein, produces progressively increasing degrees of
saturation in a given direction in the cores thereof, said second
windings being connected in series with each other to form a group
of scanning windings; biasing current means connected to said group
of biasing windings to cause said given saturating biasing current
to flow through each winding of said group of biasing windings to
saturate said cores in said first direction in progressing
increasing degrees of saturation; scanning current means connected
to said scanning windings for feeding a scanning current
therethrough which increases progressively in amplitude for
sequentially driving each core from a saturation in a given
direction through an unsaturated state to the opposite state of
saturation, the driving of each magnetic core from saturation in
said given direction to an unsaturated state occuring before the
next core is driven from its initially saturated state to provide a
detectable substantial change in an electrical output in the
windings thereof as the core thereof is separately driven from its
initial state of saturation; condition responsive means
respectively associated with each of said plurality of saturable
core devices, each of said condition responsive means being
respectively in normal and abnormal conditions when the condition
being monitored is respectively in normal and abnormal states and
in one condition thereof inhibiting the detectable substantial
change in the electrical output of the associated saturable core
device so said electrical output is absent at the instant of time
when the core would otherwise be driven from its initially
saturated state; and time and electrical output responsive means
coupled in series with one of said group of windings and responsive
to the presence or absence of an electrical output in said group of
windings at a given time for identifying the saturable core device
associated with a condition responsive means in an abnormal
condition.
11. An event monitor system according to claim 10 wherein said
biasing means is a direct current voltage source of constant
amplitude to provide a steady state of current through each of said
biasing windings.
12. An event monitor system according to claim 10 wherein said
detector means includes a plurality of annunciator control
circuits, a plurality of gate circuits each responsive to an
electrical output from a different one of said scanning windings
and a second control signal occurring at the same time as developed
by a gate control circuit for energizing an associated annunciator
control circuit between normal and abnormal conditions, an alarm
indicating means connected to each annunciator control circuit to
be operated thereby to an alarm indicating condition when said
associated annunciator control circuit is in said abnormal
condition.
13. An event monitor system according to claim 12 wherein said gate
control circuit includes a second plurality of saturable core
devices each having a first and second winding associated with a
separate magnetic core, each of said first windings being connected
in series with each other to form a group of biasing windings
which, when a given saturating current flows therein produces
progressively increasing degrees of saturation in a given direction
in the cores thereof, said second windings being connected in
series with each other to form a group of scanning windings, said
second plurality of saturable core devices being remote from said
first plurality of saturable core devices and arranged for
receiving simultaneously the biasing current from said bias current
means and the scanning current from said scanning current means
substantially in the same manner as the windings of said first
plurality of saturable core devices to generate time sequential
pulses which are applied to said plurality of gate circuits to be
coincident with particular electrical outputs from said first
plurality of saturable core devices. to open the gate at
predetermined points in time.
14. An event monitor system according to claim 12 wherein said
alarm indicating means is a visual indicating means.
15. An event monitor system according to claim 10 wherein the
detectable substantial change in the electrical output in each of
said windings is produced by a change of state of saturation of the
associated saturable core device.
Description
This invention relates to an event monitoring system for displaying
the normal and abnormal conditions of a large number of variables
or conditions being monitored by activation of condition sensor
means associated therewith.
The event monitoring system of this invention has its most useful
application in systems wherein the connections between a central
control panel and a large number of condition sensors is made over
only a few wires, and has its most important (but not its only)
utility for sensing and displaying the circuit opening and circuit
closing conditions of switching means, such as relay contacts and
electronic switches representing normal and abnormal conditions of
the devices or condition means being monitored.
One such event monitoring system of the prior art is based on a
single-series loop of switches, as in the case of burglar alarms,
all of which are closed to indicate that all doors and/or windows
of a particular building located remote from a readout panel are
secured shut. In this system, a door or window which becomes open
will cause one of the switches to be actuated to an open condition
this energizing a warning or alarm device at the central location
to indicate that a door or window has been opened. However, this
type of prior art system is not capable of indicating which
particular door or window is opened. Another type of prior art
event monitoring system provides a separate indication of the
condition of each of a plurality of variables being monitored but
these systems, which operate with single circuit opening or circuit
closing condition responsive means, require at least one line for
each condition responsive switch within the system.
Accordingly, an object of this invention is to provide an
electrical event monitoring system for sensing normal and abnormal
states of a plurality of condition responsive means which can
comprise simple circuit opening or circuit closing switches
indicating the normal and abnormal states of the variables or
conditions being monitored and wherein a minimum number of lines
are required for connecting a monitoring station to the condition
responsive means to display the information of the conditions of
all the variables or conditions being monitored.
In accordance with the most advantageous form of the invention,
there is associated with each condition responsive means a
saturable core device including a saturable core having biasing and
scanning windings wound on a common saturable core preferably
having a rectangular hysteresis characteristic, the biasing winding
of each core having a different number of turns with respect to the
biasing windings of every other core. The biasing windings are
connected in series to receive a biasing current which may be a
constant current from a contact amplitude direct current voltage
source or a varying direct current from a varying amplitude direct
current voltage source to provide the desired biasing magnetomotive
force which saturates the associated cores in different degrees
depending upon the number of turns in the biasing windings. The
scanning windings of the saturable core devices are connected in
series one with the other to receive a common progressively
increasing scanning current to develop a second magnetomotive force
in each saturable core device opposite in direction to the
magnetomotive force produced by the biasing current so that the two
magnetomotive forces subtract from one another. Therefore, the
progressively increasing scanning current may be sufficient to
cause the saturated condition of the cores of the saturable core
devices sequentially each to go from their initially saturated
state through an unsaturated state to their opposite state of
saturation, and an electrical output, such as a voltage pulse, is
generated during the momentary interval each core is in an
unsaturated state. Thus, where, for example, when there are 200
similar saturable core devices numbered 1 to 200 having biasing
windings with progressively differing numbers of turns, (e.g., 1 to
200 turns), a progressively increasing scanning current will
produce 200 electrical output signals in the windings of the
saturable core devices, the output signals occurring at 200 equally
spaced intervals over an arbitrary time base. A sensing circuit
connected in series with the serially connected scanning or biasing
windings thus can sense the presence or absence of electrical
outputs generated by all of the saturable core devices.
In one form of the invention the scanning windings are shunted by
condition responsive switches which are respectively in circuit
opening or circuit closing conditions when the associated devices
or condition means are in normal or abnormal conditions or vice
versa. Therefore, the closure of a condition responsive switch
prevents the scanning current from unsaturating the associated
saturable core device so that the absence of a pulse at a time
interval assigned to a particular saturable core device indicates
that the device or condition means being monitored is either in a
normal or abnormal condition, whichever the case may be.
The electrical output sensing circuit, the scanning and biasing
current sources, and a condition display means are most desirably
located at a central control sation. The scanning current source
may be a cyclic sawtooth current generator. The display means may
be a gate controlled annunciator system with the condition of each
event being monitored indicated by a different visible indication,
provided for example, by one or two light sources. A gate circuit
may be provided for controllably actuating a selected annunciator
control circuit in response to the simultaneous presence of a
timing and a gate signal occurring during the time interval of an
electrical output assigned to an associated saturable core device,
the presence of both signals being required. Another form of
display means which can be utilized with this invention is a strip
chart recorder of the type providing a permanent mark on a moving
paper strip whenever an electrical output is generated by a
saturable core device, so that the presence or absence of a mark at
a particular point on the strip chart quickly can identify the
condition of a particular condition responsive means during the
scanning cycle involved. The strip chart recorder may thus display
marks at numbered locations on the chart corresponding to a
particular condition responsive means being monitored.
The aforementioned gate circuits may include a decoding group of
saturable core devices of substantially a similar design and
arrangement or the group of saturable core devices located at the
remote monitoring points. In this arrangement the biasing and
scanning currents are delivered to the biasing and scanning
windings of both groups of saturable core devices. The group of
saturable core devices located at the central control station will
produce electrical outputs in the associated windings which are
coupled to the input of separate respection AND gate circuits, the
latter electrical outputs being developed at points in time
corresponding to the electrical outputs produced by the remotely
located saturable core devices when not shunted by their condition
responsive switch. The electrical outputs from the remote saturable
core devices associated with the condition responsive means being
monitored are delivered to the gate circuits through a common
signal path and coincident electrical outputs at the input of any
gate circuit will actuate the annunciator control circuit
associated therewith to operate the associated annunciator
lamp.
In one embodiment of this invention the number of saturable core
devices which can be used, hence, the number of conditions which
can be monitored, for a given amplitude of biasing and scanning
current and winding turns variation is doubled by dividing the
series connected scanning windings into two groups, the windings in
one group being wound in an opposite direction with respect to
windings in the other group. Therefore, when all the saturable core
devices are saturated in one direction by a given biasing current,
a progressively increasing scanning current of a given polarity
will generate magnetomotive forces which will be opposing the
magnetomotive forces produced by the biasing current in one group
of windings while causing aiding of the magnetomotive forces
produced by the biasing current in the other group of windings,
thus producing electrical output signals only from the one group of
windings. When a progressively increasing scanning current, or a
biasing current, of opposite polarity is applied to the two groups
of serially connected scanning, or biasing windings, the
magnetomotive forces generated in said one group of windings will
be aiding and the magnetomotive forces in said other group of
windings will be opposing, thus producing electrical output signal
only from the said other group of windings. In this arrangement
there will be two saturable core devices having the same number of
biasing winding turns but are distinguishable one from the other by
the polarity of the scanning or biasing current applied thereto,
the advantage being doubling of the number of saturable core
devices which can be used to produce electrical output signals to
identify the particular condition responsive means associated with
the particular condition event being monitored.
Other objects, features and advantages of this invention will
become more fully realized and understood from the following
detailed description when taken in conjunction with the
accompanying drawings wherein like reference numerals throughout
the various views of the drawings are intended to designate similar
elements or components.
FIG. 1 is a simplified block diagram of an event monitoring system
in accordance with this invention;
FIG. 2 is a partial schematic and partial block diagram of portions
of the event monitoring system of FIG. 1;
FIG. 2A illustrates a typical hysteresis curve which may be the
magnetic characteristic incorporated in the saturable core devices
of this invention;
FIG. 3 is a diagrammatic representation of one kind of display
readout which can be used to provide a permanent record of normal
and abnormal conditions being monitored by the system of this
invention;
FIG. 4 is a simplified block diagram of another form of display
readout that can be used in the event monitoring system of this
invention;
FIG. 5 illustrates one preferred waveform of scanning current which
can be used in conjunction with this invention;
FIG. 6 is a schematic diagram of another form of condition sensor
means which may be utilized in accordance with this invention;
FIG. 7 illustrates another preferred form of scanning current which
can be used in conjunction with this invention;
FIG. 8 is a block diagram illustrating one circuit arrangement
which can be used to form the waveshape of FIG. 7;
FIG. 9 is a schematic diagram of saturable core devices used as the
condition sensor means of this invention connected to similarly
fashioned saturable core devices used as the decoding means for
operation of a plurality of gate control circuits in accordance
with one aspect of this invention.
Seen in FIG. 1 is a simplified block diagram illustrating the basic
components of an event monitoring system constructed in accordance
with this invention. The event monitoring system is indicated
generally by reference numeral 10 and includes a central control
station 12 wherein the control display equipment 27 and 29 is
located which equipment energizes and responds to numerous
condition responsive means 22 which may be spaced many miles from
the central control station and connected thereto by wires 24, 26,
28 and 30 in a cable 18. Each condition responsive means 22 may
include a switch like a thermostat switch which has different
states for indicating the normal or abnormal condition of a device
or variable 20 being monitored, and saturable magnet core sensor
units 16 are provided for developing electrical output signals
corresponding to the state of the condition responsive means and
occurring at a point in time which identifies particular ones the
devices or variables being monitored. The unique and novel aspects
of this invention enable a relatively large number of condition
responsive means 22 (like 100 or more) switches to be monitored
with only a total of four or less interconnecting wires connecting
all of these condition responsive means 22 to the central control
station 12. Where the condition responsive means 22 are switches,
the opening and closing thereof in response to the condition by the
monitored device or variable 20 act upon the associated sensor 16
to prevent or inhibit the generation of a signal thereat. These
switches may be relay contacts or electronic switches, or any other
circuit opening and circuit closing device.
By way of example, the normal and abnormal conditions of the device
or variable being monitored 20 being monitored may be represented
by the open and closed conditions of the associated condition
responsive switch 22 (or vice versa). In this arrangement the
associated saturable magnetic core sensor 16 will produce an
electrical signal within a reference interval or cycle at a given
time assigned to the condition or variable being monitored to
indicate the normal condition of the variable. (While in accordance
with the broad aspect of the invention, the electrical signal
referred to may be the absence of an output but for the purpose of
the present exemplary description it will be assumed that the
electrical signal referred to is the presence of a voltage or
current of a given current or voltage pulse.) When the associated
variable is abnormal, the generation of such electrical signal is
inhibited. (If the condition responsive switch is to be open when
the variable being monitored is abnormal then the presence of such
a signal would indicate that the variable involved is abnormal.)
The presence or absence of an electrical signal will operate a
suitable time and signal responsive readout or annunciator means 29
connected in common with all of the saturable core sensors 16 to
indicate which variables are normal and which are abnormal. Various
saturable core operating currents are fed to one or more windings
of the saturable core sensors on one or more lines like 24 and/or
28 by core operating means 27 and the electrical output signals
referred to can be coupled to the readout or annunciator means 29
by the same or different lines. Since lines 26 and 28 may be
associated respectively with the lines 24 and 28 or a common ground
line may replace the lines 26 and 28 when a suitable earth-ground
is readily obtainable between the remote stations in the field and
central control stations.
For a better understanding of one of the unique and novel aspects
of this invention reference is now made to FIG. 2 wherein the
saturable core sensors 16 are indicated schematically. Each of the
saturable core sensors is here indicated by reference numerals
32-44 and include separate cores 32a- 44a respectively and
associated biasing windings 32b- 44b and groups of scanning
windings 32c- 44c. The saturable core sensors or devices 32-44 may
be of the toroid type but it is within the contemplation of this
invention that saturable core devices of any suitable configuration
can be used. The biasing windings 32b-44b are connected in series
one with the other so that a common biasing current from a bias
current source 48 at the central control station 12 will pass
through the biasing windings initially to saturate all of the
magnetic cores 32a-44a. In accordance with this invention, the
various biasing windings 32b-44b have a different number of turns
so as to establish in each magnetic core 32a-44a a different degree
of saturation. By way of example, the bias winding 32b may have one
turn, bias winding 34b may have two turns, bias windings 36b may
have three windings, and so on to the last device which may contain
as many windings as there are saturable core devices. The last bias
winding 44b of the last saturable core device 44 is connected to
the central control station 12 via a common line 30. The scanning
windings 32c-44c are also connected in series one with the other
for receiving a progressively increasing scanning current from a
scan current generator 50 located at the central control station
12, the scanning current preferably increasing linearly with
respect to time. The number of turns in each of the illustrated
scanning windings 32c-44c is the same. The magnetomotive force
generated by the scanning current opposes the magnetomotive force
generated by the biasing current to produce a resultant
magnetomotive force equal to the difference of the same and over
the range of values thereof will sequentially first unsaturate and
then drive each core to the opposite state of saturation (i.e., the
cores are sequentially rapidly driven from one state of saturation
to the other). This action is obtained by using saturable core
devices which have rectangular hysteresis characteristics as
illustrated in FIG. 2A, this only being illustrated by way of
example and not by way of limitation. The endmost scanning winding
44c is connected to an electrical output circuit 46 which, by way
of example, comprise a resistor 46a and a capacitor 46b. An
electrical output signal is generated as each core is unsaturated
and the scanning current as well as the output signals are
developed across the resistor 46a but only the output signals are
coupled through the capacitor 46b and line 28 to display readout
device 52 located at the central control station 12. Each of the
condition responsive switches 22 is shown connected in parallel
with one of the scanning windings, and if the condition responsive
switches are normally open the above described output signals will
be generated but the closing of a switch will short circuit the
associated scanning winding to prevent the associated core device
from being unsaturated by the scanning current. In such case, the
absence of a signal during the time interval assigned to the core
device indicating that the variable involved is abnormal. On the
other hand, if the condition responsive switches are normally
closed only a core device which is associated with an abnormal
variable will produce a signal during the assigned time interval.
The display readout device 52 is designed to give a visual
indication of the variables which are normal and/or abnormal during
each scanning cycle. Most advantageously the scan current generator
50 and display readout device 52 are operatively interrelated such
as by means of a synchronizing circuit 54 to provide a means for
identifying the time intervals during which the presence or absence
of signals occur to provide the indications of these signals and
the identification of the variables represented by these signals or
the absence of the same. Also, if desired, the display readout
device 52 may be synchronized from signals developed by the scan
current generator 50 as delivered over a line 56.
FIG. 3 shows one form of display readout device which may be
incorporated at the central control station 12. Here, the display
readout device includes a moving tape 58 which passes in proximity
to marking heads 60a and 60b which may be respectively actuated by
the electric output signals from the line 28 and 56 in FIG. 2.
Preferably, the marking head 60a generates cycle beginning markers
59 in the tape 58 from pulses in line 56 generated at the beginning
of each scanning current cycle. The marking head 60b generates
variable condition indicating markers 61 for each pulse present on
the line 28, the presence of which depends on the open or closed
condition of condition responsive switch 22 as first explained. The
tape 58 may have indicia lines 63 thereon which are marked with
numbers as indicated identifying the variable assigned to the
various time intervals within each scanning cycle or period
represented by the portion of the tape between successive cycle
beginning markers 59. Where the abnormal condition of a variable
results in the closure of the associated condition responsive
switch, the absence of a marker 61 such as at points or interval
identified by indicia line numbers 4 and 198 in FIG. 3 indicates
that the variable involved is abnormal.
Referring now to FIG. 4 there is seen a readout circuit here
designated generally by reference numeral 52b. The display readout
circuit 52b includes a gate control scanner 70 for generating
signals corresponding in time to the spaced apart signals produced
by the condition responsive means 16 of FIGS. 1 and 2, the gate
control scanner being any suitable circuit, as for example, a ring
counter or the like. Sequential output signals from the gate
control scanner 70 are delivered to respective ones of a plurality
of AND-gates 71, 72, 73 and 74. Additionally, the spaced-apart
electrical output signals on line 28 are simultaneously delivered
to all of the AND-gates 71-74 and only that AND-gate having
simultaneous input signals will be activated to an open or signal
passing condition thus applying an operating signal to an
associated bistable control circuits 76, 77, 78 or 79. By way of
example, the control circuits 76-79 may be latch relay control
circuits for energization relay coils 80, 81, 82 and 83
respectively in response to the output of the AND-gates 71-74.
Although relays are shown in the embodiment herein, it will be
understood that any suitable bistable or lock-in switching circuit
means may be used, as for example, bistable transistor or silicon
controlled rectifier circuits. Associated with each of the relay
coils 80-83 are corresponding single-pole, double-throw switches
having movable contacts 80a-83a connected to a voltage source, as
for example a positive voltage supply, and a pair of stationary
contacts 80b-80c . . . . 83b-83c thereof connected respectively to
visual indicating lamps 86 and 87. Each of the indicating lamps 86
may be a red lamp while each of the indicating lamps 87 may be a
green lamp. It will be assumed that the normal conditions of
condition responsive switch 22 is to cause energization of the
associated green lamp. If the associated relays are normally
deenergized, the presence of an abnormal condition will produce a
pulse on line 28, and such a pulse together with a corresponding
pulse from the gate control scanner 70 will energize, and lock-in
the appropriate relay coil to move the appropriate one of the
movable contactors 80a, 81a, 82a, or 83a from the contacts 80c,
81c, 82c or 83c to the contacts 80b, 81b, 82b or 83b to deenergize
the corresponding green lamp and energizing the accompanying red
lamp to readily identify the location of the abnormal condition.
Each of the control circuits 76-79 may include suitable switch
means 76a-79a or the like selectively to change the function of the
control circuit to either energize or deenergize the relay coils
80-83 during the presence or absence or an output of the associated
AND-gates 71, 72, 73 or 74, thus selectively changing which
conditions are to be indicated as normal or abnormal.
FIG. 5 illustrates an exemplary current waveform 90 developed by
the scan current generator 50 of FIG. 2 which is to be used for the
scanning current signals applied to the scanning windings 32c-44c
as illustrated, the waveform 90 has linearly increasing sawtooth
waveform portions 90a each followed by a quick return portions 90c,
portions 90a of the waveform each have points indicated by the
vertical broken lines 90b occurring at times t.sub.1, t.sub.2,
t.sub.3, etc. Within each cycle which are the instants of time when
the current waveform will cause unsaturation of the various
saturable core devices 32-44. The quick return portion 90c may be
used to develop the synchronizing or cycle beginning pulses (as by
passing the waveform through a differentiating network) and such
pulses fed to the cycle beginning marker generating head 60a in
FIG. 3.
Referring now to FIG. 6 there is seen a modified form of the
saturable core circuit of this invention and here designated
generally by reference numeral 16a. In this form the saturable core
devices are divided into two groups, one group including saturable
core devices 96, 97, 98, etc., and the other group containing
saturable core devices 96', 97', 98', etc. Their biasing and
scanning windings 96a-a', 97a-a', 98a-a', etc., and 96b-b', 97b-b',
98b-b', etc., are respectively connected in series to receive the
same biasing and scanning currents. In this arrangement, the
biasing or scanning windings of one group of saturable core devices
are wound in the opposite direction from that of the corresponding
windings in the other group of saturable core devices (windings may
be said to be wound in opposite directions if their terminal
connections are in reverse relation even though actually wound in
the same direction from a visual inspection of the same). In the
embodiment illustrated therein it is the biasing windings of the
two groups of saturable core devices which are wound in opposite
directions. In such case the direction of the electromagnetic
fields developed by the biasing windings of one group of saturable
core devices is opposite that developed by the biasing windings in
the other group of saturable core devices. This is indicated by the
upwardly directed arrowed lines adjacent the biasing windings
96a-98a, and the downwardly directed arrowed lines adjacent the
biasing windings 96a'-98a', etc. A scanning current, similar to
that shown in FIG. 5 will operate to unsaturate sequentially the
saturable cores of one group of the devices since the waveform 90
will provide a bucking electromagnetic field in one group and an
aiding electromagnetic field in the other group of saturable core
devices. A modified scanning current waveform is applied to the
scanning windings 96b-b', 97b-b', and 98b-b', etc., illustrated in
FIG. 7 which is a periodic waveform 105 having linearly increasing
positive sawtooth current waveform portions 105a between a periodic
waveform having linearly negative current waveform portions 105b.
The positive scanning current waveform portions 105a operate in the
same manner as the scanning waveform 90 of FIG. 5 to sequentially
unsaturable one of the groups of saturable core devices 96-98 and
the negative scanning current waveform portions 105b operate in the
same manner as the scanning waveform 90 of FIG. 5 sequentially to
unsaturate one of the other groups of saturable on devices
96'-98'.
FIG. 8 illustrates an exemplary circuit arrangement which provides
means for generating the current waveform 105 of FIG. 7. Here there
is provided a clock pulse generator 112 which may comprise any
suitable means for producing equally spaced apart pulses, as for
example, a free running oscillator of either the sine wave or
square wave type the output of which may be connected to a
differentiating circuit for producing the desired pulses. The clock
pulses are then delivered simultaneously to a sawtooth generator
112 and a bistable flip-flop circuit 113 via lines 112a and 112b
respectively. The sawtooth generator 112 may be of any suitable
design to produce at the output thereof the desired sawtooth
waveform as illustrated by reference numeral 106, as where, for
example, the linearly increasing portion of the sawtooth waveform
106 is developed by the initial substantially linear portion of an
exponential charging voltage across a capacitor within the sawtooth
generator 112. Also, the bistable flip-flop circuit 113 may be of
any suitable design to provide at the two output lines 113a and
114b thereof alternately appearing gate opening and gate closing
control voltages, the line 113a having a gate opening voltage and
the line 113b having a gate closing voltage during one time
interval and this condition reversing during a subsequent time
interval, and these gate opening and gate closing voltages being
developed by, for example, either a saturated or an unsaturated
flip-flop circuit having a pair of alternately conductive
transistors or the like wherein the outputs of each are
cross-coupled to the input of the other in the usual manner. The
transistors may be arranged to receive a single common input
trigger voltage, as shown here by line 112b, when the emitter
electrode of such transistors are connected together and the
trigger voltage is applied to the emitters, or the input may be
divided to provide connection to the inputs of the two transistors,
either of the above input circuit arrangements is well known in the
art. The outputs of the bistable flip-flop circuit 113, via line
113a and 113b, are connected to gate control circuits 114 and 115
which also receive the sawtooth waveform 106 and each gate circuit
114 and 115 passing ever other sawtooth waveform depending on which
of the lines 113a or 113b is in the gate opening condition.
However, at the output of gate circuit 114 there is provided an
inverter circuit which reverses the polarity of the sawtooth
waveform from gate 114. The two outputs of the gate circuits 114
and 115, one being reversed in polarity, are then recombined at an
output line 117 whereat the composite waveform 105 is
developed.
Referring now to FIG. 9 there is seen still another form of this
invention wherein a group of saturable core devices 140, 141, 142,
143, etc. are provided for location at points at a remote station.
The saturable core devices 140-143, etc. have their biasing
windings 140b-143b, etc. connected in series and their scanning
windings 140c-143c, etc. connected in series in substantially the
same manner as described hereinabove. However, in this embodiment
there is provided a plurality of decoding saturable core devices
146, 147, 148, 149, etc. of substantially the same configuration as
the saturable core devices 140-143, etc. and in a similar manner
have their biasing windings 146b-149b, etc. connected in series one
with the other and their scanning windings 146c-149c, etc.
connected in series one with the other. The biasing winding
146b-149b are connected in series with the biasing winding
140b-143b via a line 24a and the scanning windings 146c-149c are
connected in series with the scanning windings 140c-143c via a line
26a. In accordance with this aspect of the invention the saturable
core device 140 is substantially the same as the saturable core
device 146 while the saturable core device 141 is substantially the
same as the saturable core device 147 and so on thus forming two
similar groups of saturable core devices. The scanning windings
146c-149c etc. of the decoding cores are free of condition
responsive means connected in parallel therewith for shunting the
current therethrough. Therefore, during each common scanning
current signal through the two groups of scanning windings an
electrical output will be developed at each saturable core device
of the decoding group and an electrical output will be developed at
the remote monitoring group only by those saturable core devices
not shunted by their associated condition responsive switch means
22, and the electrical outputs developed by correspondingly similar
ones of saturable core devices of the two groups occurring at
substantially the same time. The electrical output signals from the
scanning windings 140c-143c, etc. are delivered to a pulse detector
and amplifier circuit 150 via a line 28a which, in turn, is
connected to the line 26a. The electrical output signals developed
on the scanning windings 146c-149c are maintained sufficiently low
in amplitude as not to affect the pulse detector and amplifier 150
to prevent erroneous condition responses at the display readout.
This can be accomplished by providing loose coupling of the winding
146c-149c, etc. or by utilizing saturable magnetic cores 146a-149a,
etc. of different materials or configurations with respect to the
saturable magnetic cores 140a-143a, etc.
The electrical signals formed at the output of the pulse detector
and amplifier 150 are delivered to a plurality of gate circuits
152, 154, 156, 158, etc. The electrical output of the decoding
saturable magnetic core devices 146-149, etc. are also delivered to
the gate circuits 152, 154, 156, 158, etc. by means of separate
signal developing windings 146d-149d, etc. respectively. The output
signal from each of the windings 146d-149d, etc., will be
coincident only with the output signal of the corresponding one of
the windings 140c-143c, etc. and only under this condition will the
appropriate gate circuit be electrically opened to pass a signal to
a corresponding one of storage circuits 162, 164, 166, 168, etc.
Here, the storage circuits 162, 164, 166, 168, etc. may correspond
in electrical function to the relay control circuits 76-79, etc. of
FIG. 4. Connected to the outputs of the storage circuits 162, 164,
166, 168, etc. are suitable display device 172, 174, 176, 178, etc.
respectively, which, if desired may correspond to the pairs of
indicating lamps 86 and 87, of FIG. 4. Accordingly, the embodiments
disclosed in FIG. 9 illustrates effective and convenient means for
accurately developing decoding electrical signals to be applied to
the AND-gates 152, 154, 156, 158, etc., the decoding signals
corresponding in time to the electrical output signals developed by
the saturable core devices located at the remote location. Also, it
will be noted that here only three electrical lines are used to
interconnect the saturable core devices at the remote location with
the central control station since the scanning current line 26a and
the electrical output signal line 28a are connected together and
may be the same line, the pulse detector and amplifier circuit 150
providing means for separating and/or distinguishing between
scanning current signals and electrical output signals.
Accordingly, this invention provides means for monitoring a
plurality of conditions between normal and abnormal states thereof
by providing suitable readout display of the condition being
monitored at a central control station, and the connections between
the central control station and a remote location are accomplished
over a minimum number of wires. Therefore, it will be understood
that variations and modifications of the exemplary embodiments
disclosed herein may be effected without departing from the spirit
and scope of the novel concepts of this invention.
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